George Bush Sr.Condition WorsensMoved to ICU

12/26/2012 4:10 PM PST

The condition of former President George H.W. Bush appears to be deteriorating ... he's been in intensive care since Sunday, and his people are hedging on his prospects for recovery, saying they're "cautiously optimistic."

88-year-old Bush was hospitalized in November due to a bronchitis-like cough, and has remained hospitalized since.

Bush suffers from a condition called vascular Parkinsonism, which Bush has described as a kind of leg paralysis where "you tell your legs to move, and they don't move." It's unclear if the condition is related to his current hospitalization.

Bush's fever has gone up in the last few days, and doctors have been unable to control it.